IMOS - Ships of Opportunity - Ocean Carbon Dioxide Data from RV Southern Surveyor voyage SS022009 Leg 1

This data was collected in April and May 2009 by the IMOS Ship of Opportunity Underway CO2 Measurement research group on RV Southern Surveyor (IMOS platform code: VLHJ) voyage SS022009 Leg 1.Departed:     Lautoka Fiji, April 22, 2009Arrived:     Nuku'Alofa, Tonga, May 18, 2009CO2 System Overview:The fugacity of carbon dioxide (fCO2) in surface seawater was measured using a General Oceanics Inc. automated system (Model 8050; Pierrot et al 2009). Seawater is sprayed into an equilibration chamber and CO2 in the headspace gas equilibrates with the seawater. The headspace gas is pumped through a thermoelectric condenser followed by a nafion drying tube before flowing through a Licor 7000 non-dispersive infrared gas analyser used to measure the CO2 mole fraction (XCO2) of the dried air. The gas flow is stopped temporarily for the CO2 measurements, which are made at atmospheric pressure. A set of four CO2 standards that cover the range of CO2 values expected in the ocean are analysed about every four hours to calibrate the gas analyser. The standard gas concentrations are on the WMO-X2007 mole fraction scale for CO2-in-air. Atmospheric XCO2 (dry) is measured after the standards by pumping clean outside air from an intake on the forward mast of the ship. Seawater intake and ancillary data:The seawater intake is located at about 5.5m depth in the bow of the ship. Sea surface salinity is measured using a thermosalinograph (Seabird Electronics SBE21) located next to the CO2 system. A remote temperature sensor (Seabird Electronics SBE 38) located at the intake is used to measure sea surface temperature (SST). The travel time between the intake and CO2 system is typically about 4 minutes with warming usually less than 0.6ºC. The thermosalinograph water is from the same intake, but the supply lines separate after the intake. A comparison of thermosalinograph and equilibrator temperature records shows the temperature difference in the two lines is generally less than 0.1ºC. The thermosalinograph water line travels outside the ship and is typically warmer than the equilibrator. The travel time in water line to the thermosalinograph is 2.5 minutes faster than to the equilibrator. Meteorological data, salinity, SST, and ships position and time are taken from the ships logging system. These parameters and the data quality are maintained by the Australian Marine National Facility.

本数据集由整合海洋观测系统（Integrated Marine Observing System, IMOS）的机遇船舶走航CO₂测量研究小组，于2009年4月至5月期间，在“南方考察者号”研究船（RV Southern Surveyor，IMOS平台代码：VLHJ）的SS022009航次第1航段采集。
启航地：斐济劳托卡，2009年4月22日
抵达地：汤加努库阿洛法，2009年5月18日

## CO₂系统概述
本研究采用通用海洋科学公司（General Oceanics Inc.）的自动化系统（型号8050；Pierrot等，2009），对表层海水的二氧化碳逸度（fCO₂）进行测定。将海水喷入平衡腔，使顶空气体中的CO₂与海水达到气液平衡。将顶空气体泵送至热电冷凝器，随后流经纳菲昂干燥管（nafion drying tube）进行干燥，再通过Licor 7000型非色散红外气体分析仪（non-dispersive infrared gas analyser），对干燥后气体的CO₂摩尔分数（XCO₂）进行测定。测量CO₂时需暂时中断气流，且所有测量均在常压下完成。每间隔约4小时，即对一组覆盖海洋环境中预期CO₂浓度范围的4种CO₂标准气体进行分析，以完成气体分析仪的校准。标准气体的浓度采用WMO-X2007空气CO₂摩尔分数标定标准。标准气体分析完成后，通过安装于船舶前桅杆的进气口抽取洁净外界空气，以此测定大气干燥态XCO₂。

## 海水取水及辅助数据
海水取水口设于船舶船首约5.5米水深处。借助置于CO₂系统旁的热盐计（Seabird Electronics SBE21）测定表层海水盐度。在取水口处安装的远程温度传感器（Seabird Electronics SBE 38）用于测定表层海水温度（Sea Surface Temperature, SST）。取水口至CO₂系统的输水行程通常约为4分钟，输水过程中水温升高一般不超过0.6℃。热盐计的取水水源与CO₂系统一致，但两条输水管道在取水口处分流。对热盐计与平衡腔的温度记录进行对比后发现，两条输水管道的水温差通常小于0.1℃。热盐计的输水管道沿船舶外壁铺设，因此水温通常高于平衡腔侧的输水管道。热盐计输水管道的行程比平衡腔侧短2.5分钟。

气象数据、盐度、SST、船舶位置及时间信息均取自船舶日志系统。上述参数与数据质量均由澳大利亚国家海洋设施（Australian Marine National Facility）负责维护。